Take a look at the website and determine what you absolutely don’t want to miss. If you arrive a little before the museum opens, yo should not have an isssue with crowds. The presidential portrait exhibit is excellent. Be sure to visit the room where Michelle Obama’s portrait is located!

No. Its free

No wait to enter. I’ve seen a 10-15 minute wait to stand in front of President Obama’s portrait (Weekend), Mrs Obama’s portrait was just crowded.

I do not believe so

Hi there : You should take a look at the National Portrait Gallery's own website. You'll find quite a lot of helpful information under the VISIT - ACCESSIBILITY section, including the following : "For your comfort, wheelchairs can be borrowed by asking the security officer stationed at each museum entrance". [It might also be a good idea to "double-check" wheelchair availability with the museum in advance of your intended visit, using the Phone and/or Email details on their website] Enjoy your visit to this wonderful museum!

I went on a Monday, not a Saturday or Sunday. I walked right in, upstairs to see Michelle Obama on the 3rd floor, then down to the 2nd floor to see her husband. Easy breezy.

As mentioned above the fastest way to get there would be to take the Metro, otherwise it's a fairly short (10 minutes or so) walk.

No, you can simply walk in. If you visit during the week it is fairly quiet and even on weekends, it doesn't feel that busy (it is so vast that you don't notice the crowds!). There is no charge, unless there is a specific exhibition. I recommend half a day at least to see it all or simply go back the following day for a couple of hours. Do not miss the presidential portrait gallery and the contemporary American artists on the top floor. Enjoy!

It’s available now but earlier the Gallery was under construction.

No I did not see it at all.